Sulfur-containing carboxylates as EP agents

ABSTRACT

Compositions are provided which are sulfurized esters of olefinic mono- or dicarboxylic acids which do not contain any allylic hydrogen atoms. Synergistic mixtures of esters sulfurized with sulfur and with sulfur monochloride and sulfur dichloride are provided. Also provided are lubricating oil compositions comprising (A) a major amount of an oil of lubricating viscosity, and (B) an amount effective to impart extreme-pressure lubricating properties to said oil of these sulfurized esters.

RELATED APPLICATION

This application is a division of U.S. application Ser. No. 592,934,filed July 3, 1975, now U.S. Pat. No. 3,970,568, which is acontinuation-in-part of U.S. application Ser. No. 500,235, filed Sept.9, 1974, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to sulfurized esters of olefinic carboxylic acidsand to lubricating oil compositions containing these sulfurized estersas extreme-pressure agents. Such compositions exhibit extreme-pressurelubricating properties and are useful in cutting oils and forlubricating relatively moving parts such as in power transmissionassemblies, gear trains and engines, particularly internal combustionengines.

Metal-cutting oils should be light-colored for good visibility of thework piece. Pleasant, or at least mild, odors are required for thehealth and comfort of the machine operator. In addition, the cuttingoils must provide extreme-pressure lubrication for the work tool inorder to provide the longest possible tool life before resharpening orreplacement. In other lubricating applications where the operator is notexposed to vapors from the oil and visibility of the lubricated part isnot crucial, color and odor of the oil may not be as important asextreme-pressure lubrication and antioxidant protection. However, odorand appearance are important to those who must prepare the lubricatingoil additives, compound the oils and handle the oils as they are beingused.

The reaction products of sulfur and olefinic compounds such as crackedwax, lard oil and sperm whale oil are dark brown or black even whendiluted to the final use levels with oil. In addition, these compoundsare malodorous, smelling of hydrogen sulfide and mercaptan by-products.Previously, light-colored, mild-smelling sulfur compounds for use incutting oils have been made by chlorination or sulfochlorinationfollowed by treatment with sodium polysulfide. This multi-step indirectprocess is expensive and, accordingly, the cutting oils preparedtherefrom are expensive.

What is needed are light-colored, mild-smelling lubricating oilcompositions which can be prepared from inexpensive materials by aninexpensive, preferably one-step, process. This invention fulfills thisneed rather nicely.

2. Prior Art

Smith, U.S. Pat. No. 2,683,119, describes compositions for impartingoiliness and film strength to lubricating oils. The compositions have atleast two esterified carboxylic acid groups and at least one sulfur atomin a thiolinkage. All of the illustrated examples of suitable acidscontain allylic hydrogen atoms.

Hutchinson et al, U.S. Pat. No. 3,740,333, disclose compositions usefulas substitutes for sperm oil. The compositions are blends oftriglycerides and wax esters. The was esters are derived fromunsaturated fatty acids containing 18, 20 or 22 carbon atoms. Thetriglycerides are of the same fatty acids. The blend of the wax esterand triglycerides is sulfurized by conventional means.

SUMMARY OF THE INVENTION

Sulfurized esters of olefinic mono- or dicarboxylic acids which do notcontain any allylic hydrogen atoms have been discovered which areexcellent additives for lubricating oils and metal working and cuttingoils. In a preferred embodiment, mixtures of sulfurized andsulfochlorinated materials are provided, the mixtures displaying asynergistic improvement in drilling torque lowering.

Lubricating oil compositions have also been discovered comprising: (A) amajor amount of an oil of lubricating viscosity, and (B) an amounteffective to impart extreme-pressure properties to the oil of thesesulfurized esters. Lubricating oil compositions containing thesesulfurized esters are relatively quite light in color and are mildsmelling. Their sulfur content provides excellent extreme-pressurelubricating properties. In addition, almost no hydrogen sulfide isevolved during preparation of the sulfurized esters; thus, anair-polluting by-product is avoided.

DETAILED DESCRIPTION OF THE INVENTION

Compositions suitable for use as additives to lubricating oils andmetal-working and cutting oils comprise sulfurized esters of olefinicmono- or dicarboxylic acids which do not contain any allylic hydrogenatoms.

The lubricating oil compositions of this invention comprise (A) a majoramount of an oil of lubricating viscosity, and (B) an amount effectiveto impart a beneficial effect, such as extreme-pressure and antiwearproperties to the oil of these sulfurized esters.

The esters from which the sulfurized esters are prepared are esters ofolefinic mono- or dicarboxylic acids and low-to-medium molecular weightalcohols, neither of which contain any allylic hydrogen atoms.

The Carboxylic Acids

As mentioned above, the esters are prepared from mono- and dicarboxylicacids which do not contain allylic hydrogen atoms. Allylic hydrogenatoms are well known to those skilled in the art. They are hydrogenatoms bonded to saturated carbon atoms which are alpha to a double bond.An example of this is shown in the following Formula I. ##STR1##

In Formula I the hydrogen marked with an asterisk is an allylichydrogen. An example of a carboxylic acid which contains no allylichydrogens is acrylic acid (CH² =CH-COOH). An example of a carboxylicacid which contains allylic hydrogens is methacrylic acid (CH²=C(CH³)-COOH). In methacrylic acid, the methyl group bonded to the alphacarbon atom is a saturated carbon atom to which are bonded hydrogenatoms. This saturated carbon atom is alpha to the double bond of acrylicacid; therefore, the hydrogen atoms on the methyl group are allylichydrogen atoms.

Examples of suitable monocarboxylic acids for use in this inventioninclude acrylic acid, 2,4-pentadienoic acid (beta-vinyl acrylic acid),4,4-dimethylpenta-2-enoic acid and other similar compounds. Suitablemonocarboxylic acids such as mentioned above can be represented by thegeneral formula ##STR2## wherein x represents 1, 2 or 3, preferably 1,and Z represents hydrogen or a hydrocarbyl radical bonded to theremainder of the carboxylic acid through a tertiary carbon atom.Examples of suitable hydrocarbyl radicals include t-butyl, t-pentyl,t-hexyl, t-octyl, t-dodecyl, t-hexadecyl, t-octadecyl and the like.Generally, the monocarboxylic acids will contain 30 or less carbonatoms. Preferably, not more than one Z substituent per moleculerepresents a hydrocarbyl radical and more preferably, all Z substituentsrepresent hydrogen.

Suitable dicarboxylic acids include fumaric acid (trans-butendioicacid), maleic acid (cis-butenedioic acid), muconic acid (hexadiendioicacid), 2-t-butyl-fumaric acid, 2-t-butyl maleic acid, 2-t-butyl muconicacid and the like. In general, suitable dicarboxylic acids useful inthis invention can be represented by the following formula: ##STR3##wherein x and Z have the same meaning as defined above for Formula II.Generally, the dicarboxylic acids will contain 30 or less carbon atoms.

Of course, for purposes of preparing the esters to be sulfurized, theanhydrides and acid halides of the above-described mono- anddicarboxylic acids can be used, and this invention contemplates theiruse. The anhydrides can be simple or mixed anhydrides and includeexternal anhydrides such as acrylic anhydride and internal anhydridessuch as maleic anhydride.

The Alcohols

Suitable alcohols which may be combined with the carboxylic acidsdescribed above to form the esters which are then sulfurized to form thecompositions of this invention include lower- to medium-chain-lengthalcohols. Suitable alcohols include lower- to medium-molecular-weightaliphatic alcohols such as the lower- to medium-molecular-weightalkanols. Examples include those containing from 1-30 carbon atoms. Thealiphatic portion of the alkanol may contain minor, sometimesadventitious, amounts of atoms other than carbon and hydrogen such asoxygen, halogen, nitrogen and sulfur. The aliphatic portion of thealcohols can be straight- or branched-chain and may contain a smallnumber of sites of unsaturation. Generally, the alcohol contains notmore than one olefinic site per alcohol molecular and preferably iscompletely saturated. If the aliphatic portion of the alcohol containsany sites of unsaturation, it should not contain any allylic hydrogens.

In general, suitable alcohols useful in preparing the compositions ofthis invention can be represented by the formula

    R-OH                                                       IV

wherein R represents the remainder of the alcohol exclusive of thehydroxyl group, suitably containing from 1 to 30 carbon atoms,preferably containing from 1 to 12 carbon atoms, and more preferablycontaining from 4 to 8 carbon atoms. R generally is aliphatic in natureand may contain olefinic sites of unsaturation as discussed above.

Suitable low- to medium-molecular weight alcohols include methanol,ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol,t-butanol, pentanol, 2-ethylhexanol, octanol, decanol, hexadecanol,octadecanol, tripropylene oxo alcohol, tetrapropylene oxo alcohol,ethoxyethanol and the like.

The Esters

The esters are formed from the above-described carboxylic acids and theabove-described alcohols. Methods of preparing these esters are wellknown to those skilled in the art. They include, for example, directcombination of the acid with the alcohol, sometimes using mineral acidcatalysis to hasten the reaction. Water may be removed to drive thereaction to completion. In other instances, acid halides or acidanhydrides can be reacted with the alcohol. Preparing the esters formsno part of this invention and need not be further illustrated.

In general, suitable esters of monocarboxylic acids useful in thisinvention can be represented by the following formula ##STR4## andsuitable esters of dicarboxylic acids useful in this invention can berepresented by the following formula ##STR5## wherein R, Z, and x havethe same meaning as defined above.

Preparation of the Sulfurized Esters

The esters can be sulfurized, generally without difficulty, simply bycombining the above-described ester and elemental sulfur, sulfurmonochloride or sulfur dichloride.

Sulfurization can be conducted at any temperature at which the reactiontakes place below the decomposition temperature of the reactants or thereaction products. It is generally preferably to conduct the reaction atan elevated temperature to increase the rate of reaction. Preferably,the reaction between the sulfur and the ester is conducted between about100° and 200° C, preferably 120°-200° C. This reaction is generallycontinued from about 0.5-48 hours, more generally from about 2-24 hours.

The reaction between the ester and sulfur monochloride or sulfurdichloride typically goes easily at lower temperatures than the reactionbetween the ester and elemental sulfur. Typically, this reaction can becarried out between about 60° and 200° C, preferably between about 80°and 180° C. The reaction is generally continued for about 0.5-48 hours,preferably 2-36 hours.

The mol ratio of sulfur or sulfur chloride to the ester can vary widely.For this purpose it is usually convenient to calculate the mols ofsulfur or its equivalent present in the sulfur chloride used perolefinic bond present in the ester. Sulfur-to-olefinic bond ratios canrange from 0.5-2:1, preferably 0.75-1.5:1. Mol ratios of approximately1:1 are preferred, since this generally leads to high sulfur contentwithout leaving excess free sulfur in the reaction product which maysettle out upon standing.

Most of the lower-molecular-weight esters are liquid at room temperatureor at least at elevated reaction temperatures. Thus, a reaction solventis not necessary. Generally, the ester and the sulfur or sulfur chlorideare simply combined in the reaction vessel and the reaction mass isheated to the desired temperature with agitation. Heating and agitationare continued throughout the reaction period, after which the product isallowed to cool to ambient temperature.

After the reaction product has cooled to ambient temperature, it may bedesirable to allow it to stand from 1 to 3 days to allow unreactedexcess sulfur to settle out. The product can then be filtered to removethis sulfur.

The filtered product thus obtained is generally suitable without furtherpurification for adding to lubricating oils, which may be then used tolubricate relatively moving parts and as cutting oils in metal-workingoperations.

For esters which are not liquids at room temperature, it is generallypreferable to use a reaction solvent. Suitable reaction solvents includeany solvent with which the ester is miscible or in which it is solubleand which does not interfere with the sulfurization reaction. Thus,solvents which contain double bonds and particularly those which containallylic hydrogens should be avoided, since this will lead both tohydrogen sulfide evolution and to dark-colored products. The solventscan be lower-boiling petroleum fractions which may be readily removedafter the sulfurization reaction if the reaction product is a liquid atroom temperature. If the reaction product is not liquid at roomtemperature, the solvent is generally not completely removed. In thislatter case, higher-boiling petroleum fractions may be desirable,particularly fractions which have approximately the same boiling rangeand viscosity range as lubricating oils to which the sulfurized estersmay be added. The diluent oil for the sulfurized ester will then simplyform a suitable part of the ultimate lubricating oil composition.

When reaction solvents are used, whether they are lower-boiling solventswhich will be removed after the reaction is complete or thehigher-boiling petroleum fractions which are not removed, it isgenerally preferable to use the least amount of solvent possible, asthis increases the concentration of the reactants. Higher concentrationsof the reactants may not only improve the reaction rate, but alsoincrease reactor capacity.

The sulfurized esters which are obtained, particularly those made fromlower-molecular-weight carboxylic acid esters such as the alkylacrylates are liquid at room temperature and have a low enough viscosityto allow pumping and easy handling at room temperature. Furthermore,these sulfurized esters are readily miscible with lubricating oils. Theyare also much lighter in color, especially after dilution in oil tonormal working levels, than ordinary sulfurized compounds made by directreaction of sulfur. In addition, these sulfurized esters have a mild andpleasant odor.

Lubricating and Cutting Oils

While the sulfurized esters of this invention which are liquid atambient temperatures can be used neat in metal-cutting and workingoperations, it is most practical and economical to dilute the sulfurizedesters with an inexpensive carrier oil.

Suitable carriers are those which are suitable for use in lubricatingoils and cutting oils. The sulfurized esters of this invention arepresent in the lubricating oils and metal working and cutting oils ofthis invention in an amount effective to impart extreme-pressurelubricating properties to the oil. Generally, the effective amount ofthese sulfurized esters in the oils ranges from about 0.1 to about 20%w,preferably from about 0.5 to about 15%w and more preferably from about 1to about 10%w. In cutting oil applications it is common to blend thesulfurized ester with the oil to obtain a specific sulfur content. Forcutting oil applications, sulfur concentrations can range from about0.1-10%w, preferably about 0.5-5%w and more preferably about 0.5-2%w.

The sulfurized esters can be prepared as concentrates. They are thenblended with a carrier oil prior to ultimate use. Those sulfurizedesters which are liquid at room temperature are generally preparedwithout a reaction solvent and, accordingly, the concentrate contains100% of the sulfurized ester. Adding diluent oils to these concentrateswould simply increase the shipping costs, generally without compensatingbenefits such as easier handling. Those sulfurized esters which are notliquid at room temperature or which are very viscous liquids at roomtemperature can be prepared as highly concentrated packages. Again, tokeep the shipping cost to a minimum, the quantity of diluent oil inthese concentrate packages is kept to a minimum. Generally, thesulfurized ester will comprise about 20 to about 95%w and preferably isat least 50%w of the concentrate package.

The lubricating oil compositions prepared by the invention contain anoil of lubricating viscosity. This oil should be an oil of a viscositysuitable for the purpose for which the final composition is intended.They are generally lubricating oil fractions of petroleum, eithernaphthenic or paraffinic base, unrefined, acid-refined, solvent-refinedor hydrocracked as required in the particular lubricating or cuttingneed. Also, synthetic oils meeting the necessary viscosity requirements,either with or without viscosity index improvers or other additives, maybe used as the base stock.

The viscosity of the lubricating or cutting oil will vary greatlydepending upon the use for which it is intended. It is well within theskill of those in the art to tailor the lubricating oil composition tothe desired specification by choosing the appropriate base stock, mixingvarious base oils, and/or compounding these oils or mixtures thereofwith various viscosity index-improving agents commercially available.

In addition to the sulfurized ester described in this invention, theoils, particularly lubricating oils, can contain a variety of othercompounding agents such as dispersants, detergents, extreme-pressureagents, viscosity index-improvers, and other materials known to beuseful in compounding lubricating oils to meet the various exactingspecifications demanded by the particular use to which the lubricatingoil is to be put.

For metal-working operations, the lubricant compositions of thisinvention can be applied to the metal prior to the working operation inany suitable manner which insures thorough contact of the surface of themetal. For example, the lubricant can be brushed or sprayed on themetal, or the metal can be immersed in a bath of the lubricant.

The following examples are included for further understanding of theinvention.

EXAMPLES EXAMPLE 1

To a 2-liter resin flask equipped with a stirrer, nitrogen inlet,condenser, thermometer and an Ascarite-filled gas absorption tube wasadded 842 grams (4.576 mols) of 2-ethylhexyl acrylate and 146 grams(4.576 mols) of elemental sulfur. With agitation, the reaction mass washeated to 160° C under a nitrogen blanket for 21 hours at which time thereaction mass was cooled to ambient temperature and filtered throughCelite 545. 955 grams of filtrate were recovered which had a sulfurcontent of 14.0%w.

EXAMPLE 2

To a 1-liter glass resin flask equipped as in Example 1 was added 184grams (1 mol) of 2-ethylhexyl acrylate and 32 grams (1 mol) of elementalsulfur. With agitation, the reaction mass was heated to 160° C under anitrogen blanket and maintained between 160° and 170° C for 14 hours.The reaction mass was cooled and filtered to yield 206 grams of productcontaining 13.5%w sulfur.

By a similar procedure, sulfurized butyl acrylate was prepared frombutyl acrylate and elemental sulfur. The reaction product obtainedcontained 20%w sulfur.

Similarly, sulfurized di-n-butyl fumarate was obtained from di-n-butylfumarate and elemental sulfur. The product contained 10.9%w sulfur. In asimilar manner, di-n-butyl maleate was reacted with elemental sulfur.NMR analysis showed the maleate isomerized to the fumarate.

By a similar procedure, cellosolve acrylate (ethoxyethyl acrylate) wassulfurized with elemental sulfur to yield a product containing 17.7%wsulfur.

EXAMPLE 3

To a 1-liter glass resin flask equipped as in Example 1 was charged 368grams (2 mols) of 2-ethylhexyl acrylate. With stirring, 135 grams (1mol) of sulfur monochloride was added from a dropping funnel over a20-minute period. No exotherm was observed. The reaction mass was heatedwith agitation under a nitrogen blanket to 120°C and maintained at thistemperature, plus or minus 5° C, for 22 hours. At the end of thereaction period the reaction mass was cooled to room temperature andfiltered with the aid of a vacuum to yield 453 grams of filtratecontaining 10.99%w chlorine and 7.67%w sulfur and 27 grams of filterresidue which contained 97.1%w sulfur and less than 0.2%w chlorine. Thefilter residue had a melting point of 113°-114° C.

EXAMPLE 4

A. In order to insure that commercial sulfur dichloride was pure, aportion of the material was chlorinated as follows: 5352 g of commercialsulfur dichloride from Stauffer Chemical Company was placed in a largevessel and cooled to 10° C. 363 g of chlorine was added to the materialover a period of 3 hours, while the temperature was maintained at 8°-10°C.

B. A 20,000-g portion of 2-ethylhexyl acrylate was placed in a largevessel equipped with stirring and heating means. A 5605-g portion of theproduct of A was added with stirring over a period of 15 minutes. Duringthis time the temperature was 23.9° C. After 15 minutes, the temperaturehad increased to 76.7° C. After an additional 13 minutes, thetemperature had increased to 111.1° C and after an additional 7 minuteshad dropped to 108.9° C. The mixture was then heated to about 130° C andmaintained at that temperature with stirring for 24 hours. The mixturewas then cooled to 15.6° C and filtered through a 3-microncartridge-type filter.

The yield of material was 23,770 g. The product contained 6.41% byweight sulfur and 11.2% by weight chlorine.

EXAMPLE 5 -- DRILLING TORQUE TEST

The compounds prepared above were tested for their properties asadditives for cutting oils in the Drilling Torque Test. In this test adrill press with variable power feed and a variable speed is used. Adrilling torque measuring system comprised of a rotating work pieceholder, a table, a torque arm, a strain gauge, a load cell, and arecorder is used. The drill bits are high speed, steel, jobbers-lengthdrills, 3/8 inch diameter, preground to 130° cutting edge. The drillingtest material is type 304 stainless steel used in 6 inches × 6 inches ×11/2 inch blocks.

The torque measuring system is calibrated to zero and the final stoppingpoint of 110 inch-pounds of torque is determined.

A precision ground drill is securely tightened in the drill press chuck.The drill feed rate is set at 0.014 inch per revolution. The drill pressis adjusted for the desired rate of revolution and the oil pump isstarted. The drill is manually lowered until it is almost touching thetest block. The automatic feed is then engaged and a hole is drilled.When the hole is complete, the drill bit is raised, the work block isrotated and a new hole is drilled. This procedure is continued at theconstant selected rate of revolution until the drilling torque exceedsthe limit of 110 inch-pounds or until 50 holes have been drilled with asingle drill bit. Table I shows the results of testing severalsulfurized compounds prepared according to this invention as well as onecommercially available cutting oil additive. In addition, combinationsof the esters sulfurized with sulfur and with sulfur monochloride andsulfur dichloride were tested.

                                      TABLE I                                     __________________________________________________________________________    Drilling Torque Test                                                          Additive at  Sulfur Content                                                                        Additive Con-                                                                        Holes Drilled at                                  0.8%w S or   of Additive,                                                                          centration in                                                                        RPM                                               Test                                                                              (S + Cl) %w      Test Oil, %w                                                                         600                                                                              800                                                                              1000                                        __________________________________________________________________________    1   Commercially                                                                  available                                                                     cutting oil                                                                   additive 46      2      24  1  0                                              Acrylate                                                                  2(A)                                                                              Butyl +                                                                        1 mol S*                                                                              20      4       2  1  1                                          3(B)                                                                              2-Ethylhexyl +                                                                 1 mol S 14      5.7    26  6  1                                          4(C)                                                                              2-Ethylhexyl +                                                                 1.3 mol S                                                                             20      4      38 27  1                                          5(D)                                                                              2-Ethylhexyl +                                                                 0.5 mol Mono-                                                                         7.7 S   4      50+                                                                              25  5                                               chloride                                                                              11% Cl                                                           6(E)                                                                              2-Ethylhexyl +                                                                 0.5 mol         4      -- 30  8                                               dichloride                                                               7   C'** and D                                                                             --      2.5 C',                                                                              50+                                                                              50+                                                                              19                                                               2.0 D                                                    8   C'       16      5      -- 27  4                                          9   C' and E --      2.0 E                                                    __________________________________________________________________________     *Indicates mols of sulfurizing agent per mole of olefinic bonds in the        carboxylate.                                                                  **Cr' was the same as C prepared with 1.1 mol of S per mol of ester.     

From the above data it can be seen that the sulfurized esters of thisinvention impart to lubricating oils excellent properties for metalcutting operations. In particular, the sulfurized 2-ethylhexyl acrylatesexhibited properties far superior to the commercially available cuttingoil additive in the Drilling Torque Test, and the combinations of esterssulfurized with sulfur alone and with the sulfur chlorides are superiorto each employed by itself. This Drilling Torque Test has been foundfrom experience to correlate well with actual field operations.

EXAMPLE 6

Several of the above sulfurized carboxylates were tested to determinetheir effectiveness as motor oil additives.

Copper Strip Corrosion Test

The Copper Strip Corrosion Test determines corrosivity of lubricatingoils towards nonferrous metals. In this test a copper strip is immersedinto a lubricating oil composition containing the test additive. Thelubricating oil composition is maintained at 250° F (121° C) for 3hours. The degree of discoloration of the copper strip is obtained froma comparison chart. A rating of 1a indicates a very low degree ofdiscoloration and consequently very slight corrosivity of thelubricating oil composition towards copper. Ratings of higher numberssuch as 1b or 2a show higher reactivity, which may be desirable for oilsused under heavy loads. Further details of this test may be determinedby reading ASTM Test Method D-130. The results of testing thecompositions of this invention in the Copper Strip Corrosion Test areset forth in Table II.

Oxidator B Test

The stability of an oil composition against oxidative change is measuredby the time required for the consumption of one (1) liter of oxygen by100 grams of a test oil at 340° F (171° C). For convenience, the actualtest uses 25 grams of oil and the results are corrected to a 100-gramsample. A catalyst containing a mixture of soluble salts is added to theoil which provides 95 parts per million (ppm) copper, 80 ppm iron, 4.8ppm manganese, 1100 ppm lead and 49 ppm tin. Table II reports valuesobtained from subjecting the lubricating oil compositions of thisinvention to the Oxidator B Test.

Four-Ball Wear Test

Antiwear properties of lubricating oil additives under boundarylubrication conditions can be determined by means of the well-knownFour-Ball Test. In this test three 1/2 inch-diameter steel balls areclamped together and immersed in the test lubricant. A fourth steel ballis rotated at about 1800 rpm in contact with three other balls. Aspecified load, in this case 20 kilograms, is applied, forcing therotating ball against the three stationary balls. The test is run for 60minutes and the sizes of the wear scars on the three stationary ballsare measured and the average scar size in millimeters is reported. Thesmaller the scar, the greater the antiwear properties of the testlubricant. For example, base oils commonly give wear scars of 0.60 mm orgreater at 20-kg load. Generally lubricants which give a wear scar ofless than 0.5 mm at 20-kg load are considered acceptable antiwear agentsand lubricants which give wear scars of less than 0.4 mm at 20 -kg loadare considered exceptionally good antiwear lubricants. Table II setsforth the results of testing lubricating oil compositions according tothis invention in the Four-Ball Wear Test.

Falex Extreme Pressure Test

The capability of lubricating oil compositions to lubricate underextreme pressures can be measured by this test. The Falex machine ismanufactured by the Faville-LeValley Corporation of Chicago, Illinois.In this test two opposing stationary V-blocks are pressed by anutcracker arrangement of lever arms towards each other against aninterposing rotating steel shaft. The rotating shaft is driven by achuck through a brass shear pin. The V-block and pin test specimens areimmersed in a vessel of the test lubricant at a preselected temperature.The machine is operated 290 rpm and the specimens are broken in at 300pounds loading. During the test, loading between the V-blocks and therotating pin is increased automatically until seizure occurs. Thisfailure point is indicated by sheering of the brass pin holding therotating shaft. The load at failure in pounds is taken as a quantitativemeasure of the extreme-pressure properties of the oil compositions.Mineral oils may fail at 600 to 900 pounds. Oils with moderateextreme-pressure additives will fail at 1000 to 2000 pounds and veryeffective extreme-pressure additives will permit loadings in excess of3000 pounds. The limit of the test machine is 4500 pounds. The resultsof testing oil compositions of this invention in this test are set forthin Table II.

Lubricating oil compositions according to this invention were preparedfrom sulfurized butyl acrylate containing 20%w sulfur and sulfurized2-ethylhexyl acrylate containing 19%w sulfur. These sulfurized additiveswere added to a base oil which was a neutral, solvent-refinedlubricating oil having a viscosity of 480 SUS at 100° F. This base oilcontained 6%w of a polyisobutenyl succinimide produced by reactingsuccinic anhydride substituted with a polybutenyl group having a numberaverage molecular weight of about 950 with tetraethylene pentamine at anamine to succinic anhydride mol ratio of about 0.87. The base oil alsocontained 0.1%w of terephthalic acid. The results of testing this baseblend in the above-described tests are also set forth in Table II.

                                      TABLE II                                    __________________________________________________________________________                Concentra-                                                                          Cu Strip at                                                                          Oxidator                                                                           4-Ball Wear at                                                                        Falex EP,                                 Additive  tion, %w                                                                            250° F, 3 Hr.                                                                 B, Hr.                                                                             20 kg, mm                                                                             Lb                                      __________________________________________________________________________    Base Blend  --    1a     0.5  0.65    950                                     Sulfurized Butyl                                                                          1     4c     3.0  0.38     4500+                                   Acrylate (20% S)                                                                         2     4c     4.6  0.46     4500+                                              4     4c     4.3  0.44    3380                                    Sulfurized 2-Ethylhexyl                                                                   1     4c     4.1  0.39    1580                                     Accrylate (19% S)                                                                        2     4c     5.1  0.44    3180                                                4     4c     5.0  0.51    2480                                    __________________________________________________________________________

As can be seen from the above data, the lubricating oil compositions ofthis invention provide excellent antioxidation properties, antiwearprotection and extreme-pressure protection. However, copper corrosivityis relatively high but no higher than that found in somesulfur-containing lubricating oil used successfully as motor oils.

EXAMPLE 7 -- BEARING WEIGHT LOSS TEST

A lubricating oil composition of this invention was tested in the L-38Bearing Weight Loss Engine Test. In this test the lubricating oil usedcontained 6%w of the same polyisobutenyl succinimide described above inExample 5, 0.1%w terephthalic acid, 0.8%w tetrapropenyl succinic acid,1%w of sulfurized diparaffin polysulfide (17.5%w sulfur), 1.5%w ofsulfurized 2-ethylhexyl acrylate containing approximately 19%w sulfurand 0.1%w benzotriazole as a copper deactivator. In this test the testoil had a copper corrosivity rating of 3a, a significant improvementover the 4c rating shown in Table II, and a bearing weight loss after 40hours of 33 mg. In this test a bearing weight loss of less than 40 mgafter 40 hours of operation is acceptable.

EXAMPLE 8

The tests of Example 6 were repeated on lubricating oil compositions ofthis invention. In this series of tests the base oil contained noadditional additives. The base oil was a solvent-refined neutrallubricating oil having a viscosity of 480 SUS at 100° F. The results ofthe test are set forth in Table III.

                                      TABLE III                                   __________________________________________________________________________    SULFURIZED ACRYLATES AND FUMARATES                                                        Product   Tests                                                   Additive -      Analysis                                                                            Concen-                                                                            Oxidator B,                                                                         4-Ball                                                                              Falex EP,                              Reactant Mole Ratio                                                                       Color                                                                             S, %                                                                             Cl, %                                                                            tration, %                                                                         Hr.   Wear, mm                                                                            Lb                                     __________________________________________________________________________    None (480 Neutral Oil)     0.5   0.76   900                                   Acrylates                                                                     n-Butyl Acrylate/S                                                                        Lt. Br.                                                                           20    1*   2.3   0.47  1850                                                         2    6.0   0.56  2160                                   2(n-Butyl Acrylate)/                                                           S.sub.2 Cl.sub.2                                                                         Tan -- -- 2                                                       2-Ethylhexyl Acrylate/S                                                                   Tan 14    1.5* 3.1   0.40                                                               2    3.3   0.42  2180                                   2(2-Ethylhexyl Acryl-                                                          ate)/3 S   Lt. Br.                                                                           19    2                >4500                                  Ethoxyethyl Acrylate/S                                                                    Lt. Br.                                                                           18    1.1* 2.5   0.44  2130                                   2(2-Ethylhexyl Acryl-                                                          ate)/S.sub.2 Cl.sub.2                                                                    Tan  7.7                                                                             11 1    5.5   0.46  4100                                                         2.6* 9.9   0.42  3820                                   Dibasic Acid Ester                                                            Di-n-butyl Fumarate/S                                                                     Lt. Br.                                                                           11    1.7* 2.1   0.44  2430                                                         2.0  2.4   0.43  2160                                   __________________________________________________________________________     *At constant 0.2% S level in oil blend.                                  

As can be seen from the above data, the lubricating oil compositions ofthis invention possess excellent antioxidant, antiwear andextreme-pressure lubricating properties.

What is claimed is:
 1. A composition comprising the reaction product ofsulfur, sulfur monochloride or sulfur dichloride and an ester of anolefinic mono- or dicarboxylic acid which does not contain any allylichydrogen atoms and mixtures of said reaction products.
 2. A compositionof claim 1 wherein said acid contains from 3 to 200 carbon atoms and theremainder of the alcohol of said ester contains 1 to 30 carbon atoms. 3.A composition of claim 2 wherein said product contains from 0.5 to 2mols of sulfur per olefinic bond of said acid.
 4. A composition of claim3 wherein said ester of an olefinic monocarboxylic acid has the formula##STR6##and said ester of an olefinic dicarboxylic acid has the formula##STR7## wherein:
 1. x represents 1 or 2,2. each R independentlyrepresents the remainder of an esterified alcohol containing from 1 to30 carbon atoms, said
 3. each Z independently represents hydrogen or ahydrocarbyl group not containing any allylic hydrogen atoms.
 5. Acomposition of claim 4 wherein each R independently represents theremainder of an esterified alcohol containing from 1 to 12 carbon atomsand each Z independently represents hydrogen or a hydrocarbyl containingfrom 4 to 30 carbon atoms.
 6. A composition of claim 5 wherein said Rindependently represents the remainder of an esterified alcoholcontaining from 4 to 8 carbon atoms and each Z represents hydrogen.
 7. Acomposition comprising a mixture of (A) the reaction product of sulfurwith an ester of an olefinic mono- or dicarboxylic acid which does notcontain any allylic hydrogen atoms, and (B) the reaction product ofsulfur monochloride or sulfur dichloride and said ester.
 8. Thecomposition of claim 7 in which (B) is the reaction product of the esterand sulfur dichloride.